Not applicable.
Not applicable.
1. Field of the Invention
The present invention generally relates to computer systems using hot pluggable circuit boards and more particularly to a combination mechanical latch and connection signaling device for such boards.
2. Background of the Invention
Computer systems typically include a number of printed circuit boards (PCBs) that are plugged into sockets on a motherboard or backplane. Various components such as memory chips are carried on such PCBs. The computer""s functional capabilities can be increased by adding new boards to open sockets and can be upgraded by replacing existing boards with new ones. The capacities of individual random access memory (RAM) chips are constantly increasing and it is common for computer owners to increase a computer""s RAM by adding new memory boards when empty memory sockets are available, or replacing older lower capacity memory boards with new high capacity boards.
To avoid damage to boards being plugged into a computer system, it has in the past been required that the computer be powered down and preferably unplugged from its power source before any board additions are made. Newer boards, particularly memory boards, have been developed which may be plugged into a computer system while it is powered up and operating, without damage to the board. However, such hot pluggable boards do not avoid disruption of existing computer operations when an old board is removed to make room for a replacement board. To avoid such disruption, the main computer operating system needs to be notified that a board is about to be removed. With proper notification that a memory board is to be unplugged, the computer""s memory management system can move any stored programs or data to other memory and continue operating.
It would therefore be desirable to provide a device for notifying a computer operating system in advance of the insertion or removal of hot pluggable boards and for preventing removal without such notification.
The problems noted above are solved in large part by a combination mechanical latch and electrical switch. The switch portion of this combination comprises a rotary electrical switch, typically a two-position switch, with a hole through its axis of rotation. The latch portion comprises a shaft with a knob on one end for manual actuation. The shaft passes through the hole in the switch and is coupled to the rotating contactor of the switch. The rotating contactor acts as a bearing for the rotation of the shaft. A pawl that provides a latching/unlatching action can be attached to the shaft or can be an integral part of the knob. The pawl causes the latch to be mechanically engaged when the switch is in one position and mechanically disengaged when the switch is in the other position. Mechanical latching and unlatching are achieved approximately simultaneously with electrical switching. The latch/switch combination can be used to prevent the removal of a component of an electronic computing system until the switch signals the computer""s operating system that the removal is about to occur.